02 dicembre 2014

What and Why

A quick background:

  • Among young adults (15-29), suicide accounts for 8.5% of all deaths: second leading cause of death (after traffic accidents).
  • Among adults (30-49) suicide accounts for 4.1% of all deaths: fifth leading cause of death (latest "Prevent Suicide" report by WHO).

  • "The debate about the impact of climate change on human health has, very recently, included consideration of mental health" (Berry, Bowen & Kjellstrom, 2009).

  • The mental health vs climate relationship still needs to be studied into details (research gap).

Research question:

How do climate factors affect suicide rate in the Italian context?

  • Is suicide rate lower whereby the average temperature is higher?
  • Is suicide rate higher whereby the average temperature range is higher?
  • Is suicide rate higher whereby precipitations happen more frequently?

Methodology

Case selection:

Previous study: regional data, 20 observations, unsignificant model.

Now, Italy is still our focus: county-level data provide 110 observations!

<<<<<<< Updated upstream

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Our Model:

\[ <<<<<<< Updated upstream StdSuicideRate = \alpha + \beta_{1}GdpPerCapita + \beta_{2}Unemployment ======= SuicideRate = \alpha + \beta_{1}GdpPerCapita + \beta_{2}UnemploymentRate >>>>>>> Stashed changes \] \[ + \beta_{3}Population + \beta_{4}GiniIndex + \beta_{5}AverageTemperature \] \[ + \beta_{6}AverageTemperatureRange + \beta_{7}AveragePrecipitations + e \]

A Second, improved, model:

\[ <<<<<<< Updated upstream StdSuicideRate = \alpha + \beta_{1}GdpPerCapita + \beta_{2}Population \] \[ + \beta_{3}AverageTemperature + \beta_{4}AveragePrecipitations + e \]

Results

Models Comparison:

======= SuicideRate = \alpha + \beta_{1}GdpPerCapita + \beta_{2}UnemploymentRate \] \[ + \beta_{3}AveragePrecipitations + \beta_{4}AverageTemperature \] \[ + \beta_{5}Population + e \]

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Findings

First Model Second Model
GDP per capita*** GDP per capita***
Unemployment Rate dropped
Population*** Population***
Gini index dropped
Avg Temperature Avg Temperature
Avg Temp. Range dropped
Avg Precipitations*** Avg Precipitations***
>>>>>>> Stashed changes
Models Comparison
Dependent variable:
St. suicide rate
(1) (2)
GDP per capita 0.699*** 0.529***
(0.211) (0.117)
Unemployment rate 0.086
(0.106)
Population -0.174*** -0.158***
(0.043) (0.039)
Gini index 0.173
(0.487)
Average Temperature -0.072 -0.069
(0.097) (0.092)
Temperature range -0.066
(0.211)
Average Precipitations -0.435*** -0.461***
(0.147) (0.143)
Constant 5.312*** 5.622***
(1.415) (1.123)
Observations 103 103
R2 0.372 0.365
Adjusted R2 0.326 0.339
Residual Std. Error 0.264 (df = 95) 0.261 (df = 98)
F Statistic 8.041*** (df = 7; 95) 14.090*** (df = 4; 98)
Note: p<0.1; p<0.05; p<0.01

Findings:

  • Average temperatures and Temperature range have no impact on suicide rate across Italy

  • GDP per capita has a positive impact on suicides (in Italy).

  • Population size has a negative impact on suicides.

  • Annual precipitations has a negative impact on suicides.

Predicted Probabilities:

Conclusion:

  • Climate characteristics do affect suicide rates in Italy.

  • Correlation not as strong as (we) would have expected.

  • Rain actually has a negative impact on suicidial behaviour (contrary to what is commonly believed).

  • A one percentage increase in average precipitations decreases suicide rate by 0,461 percent.

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Limitations and Further Research:

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  • Data: only 2009. Panel data analysis?

  • Further applications to test whether precipitations and sucide rates are negatively correlated also in other developed countries.

  • Test other climatic factors (e.g. solar radiation)?

  • Test it with monthly data looking for seasonal patterns for suicide.

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Thank you for your attention!

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Conclusion

-Climate characteristics affect suicide rates in Italy -Correlation not as strong as (we) would have expected -Rain actually has a negative impact on suicidial behaviour (contrary to what is commonly believed)

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